 import json
import sqlite3

# Connect to database
conn = sqlite3.connect('rosterdb.sqlite')
cur = conn.cursor()

# Drop existing tables
cur.execute('''
DROP TABLE IF EXISTS User;
''')

cur.execute('''
DROP TABLE IF EXISTS Member;
''')

cur.execute('''
DROP TABLE IF EXISTS Course;
''')

# Create tables
cur.execute('''
CREATE TABLE User (
    id  INTEGER NOT NULL PRIMARY KEY AUTOINCREMENT UNIQUE,
    name    TEXT UNIQUE
);
''')

cur.execute('''
CREATE TABLE Course (
    id  INTEGER NOT NULL PRIMARY KEY AUTOINCREMENT UNIQUE,
    title   TEXT UNIQUE
);
''')

cur.execute('''
CREATE TABLE Member (
    user_id     INTEGER,
    course_id   INTEGER,
    role        INTEGER,
    PRIMARY KEY (user_id, course_id)
);
''')

# Read data from JSON file
filename = input('Enter file name: ')
if len(filename) < 1: filename = 'roster_data.json'

# Load JSON data
data = open(filename).read()
json_data = json.loads(data)

# Insert data into tables
for entry in json_data:
    name = entry[0]
    title = entry[1]
    role = entry[2]

    # Insert User
    cur.execute('''
    INSERT OR IGNORE INTO User (name)
    VALUES (?)
    ''', (name,))

    # Insert Course
    cur.execute('''
    INSERT OR IGNORE INTO Course (title)
    VALUES (?)
    ''', (title,))

    # Get User ID and Course ID
    cur.execute('''
    SELECT id FROM User WHERE name = ?
    ''', (name,))
    user_id = cur.fetchone()[0]

    cur.execute('''
    SELECT id FROM Course WHERE title = ?
    ''', (title,))
    course_id = cur.fetchone()[0]

    # Insert Member
    cur.execute('''
    INSERT OR REPLACE INTO Member (user_id, course_id, role)
    VALUES (?, ?, ?)
    ''', (user_id, course_id, role))

    # Commit changes
    conn.commit()

# Execute queries
sql = '''
SELECT User.name, Course.title, Member.role FROM 
    User JOIN Member JOIN Course 
    ON User.id = Member.user_id AND Member.course_id = Course.id
    ORDER BY User.name DESC, Course.title DESC, Member.role DESC LIMIT 2;
'''

for row in cur.execute(sql):
    print(row[0], row[1], row[2])

sql = '''
SELECT 'XYZZY' || hex(User.name || Course.title || Member.role ) AS X FROM 
    User JOIN Member JOIN Course 
    ON User.id = Member.user_id AND Member.course_id = Course.id
    ORDER BY X LIMIT 1;
'''

for row in cur.execute(sql):
    print(row[0])

# Close connection
cur.close()
conn.close()

created 2 years ago

Python Online Compiler

Write, Run & Share Python code online using OneCompiler's Python online compiler for free. It's one of the robust, feature-rich online compilers for python language, supporting both the versions which are Python 3 and Python 2.7. Getting started with the OneCompiler's Python editor is easy and fast. The editor shows sample boilerplate code when you choose language as Python or Python2 and start coding.

Taking inputs (stdin)

OneCompiler's python online editor supports stdin and users can give inputs to programs using the STDIN textbox under the I/O tab. Following is a sample python program which takes name as input and print your name with hello.

import sys
name = sys.stdin.readline()
print("Hello "+ name)

About Python

Python is a very popular general-purpose programming language which was created by Guido van Rossum, and released in 1991. It is very popular for web development and you can build almost anything like mobile apps, web apps, tools, data analytics, machine learning etc. It is designed to be simple and easy like english language. It's is highly productive and efficient making it a very popular language.

Tutorial & Syntax help

Loops

1. If-Else:

When ever you want to perform a set of operations based on a condition IF-ELSE is used.

if conditional-expression
    #code
elif conditional-expression
    #code
else:
    #code

Note:

Indentation is very important in Python, make sure the indentation is followed correctly

2. For:

For loop is used to iterate over arrays(list, tuple, set, dictionary) or strings.

Example:

mylist=("Iphone","Pixel","Samsung")
for i in mylist:
    print(i)

3. While:

While is also used to iterate a set of statements based on a condition. Usually while is preferred when number of iterations are not known in advance.

while condition  
    #code

Collections

There are four types of collections in Python.

1. List:

List is a collection which is ordered and can be changed. Lists are specified in square brackets.

Example:

mylist=["iPhone","Pixel","Samsung"]
print(mylist)

2. Tuple:

Tuple is a collection which is ordered and can not be changed. Tuples are specified in round brackets.

Example:

myTuple=("iPhone","Pixel","Samsung")
print(myTuple)

Below throws an error if you assign another value to tuple again.

myTuple=("iPhone","Pixel","Samsung")
print(myTuple)
myTuple[1]="onePlus"
print(myTuple)

3. Set:

Set is a collection which is unordered and unindexed. Sets are specified in curly brackets.

Example:

myset = {"iPhone","Pixel","Samsung"}
print(myset)

4. Dictionary:

Dictionary is a collection of key value pairs which is unordered, can be changed, and indexed. They are written in curly brackets with key - value pairs.

Example:

mydict = {
    "brand" :"iPhone",
    "model": "iPhone 11"
}
print(mydict)

Supported Libraries

Following are the libraries supported by OneCompiler's Python compiler

Name	Description
NumPy	NumPy python library helps users to work on arrays with ease
SciPy	SciPy is a scientific computation library which depends on NumPy for convenient and fast N-dimensional array manipulation
SKLearn/Scikit-learn	Scikit-learn or Scikit-learn is the most useful library for machine learning in Python
Pandas	Pandas is the most efficient Python library for data manipulation and analysis
DOcplex	DOcplex is IBM Decision Optimization CPLEX Modeling for Python, is a library composed of Mathematical Programming Modeling and Constraint Programming Modeling